Code that uses the `unsafe` keyword can be safe, though.

Yes, but you are on your own, and future maintainers will also be on their own.

The exact same way all other parts of the code is. You are also on your own in case of any logic bugs, which may well be likely even worse to debug.

Yes, but an important reason to migrate a solution to Rust are the guarantees that it offers with respect to safety.

Those guarantees go away if you use "unsafe". In that case, you may just use C or C++.

Small, encapsulated uses of unsafe wrapped in a safe wrapper are entirely different than thousands of lines of unsafe.

Also - many of the borrow checker’s guarantees are enforced inside unsafe as well.